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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 19 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.734 − 604 =
  2. 2.899 − 796 =
  3. 3.671 + 473 =
  4. 4.252 + 462 =
  5. 5.805 − 589 =
  6. 6.297 + 472 =
  7. 7.699 + 133 =
  8. 8.433 + 525 =
  9. 9.192 + 368 =
  10. 10.536 + 303 =
  11. 11.874 − 482 =
  12. 12.835 − 521 =
  13. 13.697 + 678 =
  14. 14.738 + 363 =
  15. 15.477 + 313 =
  16. 16.539 − 156 =
  17. 17.715 − 513 =
  18. 18.600 − 209 =
  19. 19.610 − 511 =
  20. 20.652 + 527 =
  21. 21.674 + 215 =
  22. 22.195 + 173 =
  23. 23.670 − 255 =
  24. 24.565 + 329 =
  25. 25.625 − 355 =
  26. 26.687 + 211 =
  27. 27.440 − 286 =
  28. 28.819 − 247 =
  29. 29.968 − 579 =
  30. 30.523 − 232 =
  31. 31.307 + 194 =
  32. 32.503 + 123 =
  33. 33.745 − 125 =
  34. 34.220 + 515 =
  35. 35.203 + 617 =
  36. 36.498 + 417 =
  37. 37.651 + 282 =
  38. 38.495 − 138 =
  39. 39.174 + 602 =
  40. 40.776 − 424 =

Answer key

  1. 130
  2. 103
  3. 1144
  4. 714
  5. 216
  6. 769
  7. 832
  8. 958
  9. 560
  10. 839
  11. 392
  12. 314
  13. 1375
  14. 1101
  15. 790
  16. 383
  17. 202
  18. 391
  19. 99
  20. 1179
  21. 889
  22. 368
  23. 415
  24. 894
  25. 270
  26. 898
  27. 154
  28. 572
  29. 389
  30. 291
  31. 501
  32. 626
  33. 620
  34. 735
  35. 820
  36. 915
  37. 933
  38. 357
  39. 776
  40. 352

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